Art of distilling lubricating oils



April 3, 1928.

R. W. HANNA ART oF DISTILLING LUBRICATING OILS Filed 06%,.4, 1923 4Sheets-Shea?l l gnvmxfo Gnome? lll Aprila, 192s.

4 SheetsSheet 2 Filed 001:.4, 1923 E Nw R W HANNA ART OF DISTILLINGLUBRICATING OILS 4 Sheecs--Sheei'I 3 @N t" lill April 3, 1928.

y R. W. HANNA ART 0F DISTIVLLING LUBRICATING o'ILs Filed mp4, 1923 April3, 1928.

R. w. HANNAf ART 0F DISTILLING LUBRICATING OILS Filed 0011.4, 1925 4Sheets-5h66?l 4 gyn/sentez Patented Apr. 3, 1928. l

UNITED STATES PATENT OFFICE.

RICHARD W. HANNA,KOF PIEDMONT, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGN-MENTS, TO STANDARD OIL COMPANY F CALIFORNIA, OF SAN FRANCISCO, CALI-FORNIA, .A CORPORATION 0F DELAWARE.

Amor DISTILLING LUBRICATING oI`Ls.U

Application inea october 4,

This invention relates to improvements in the art of distillingpetroleum oils and has to do particularly with the distillation undervacuum of lubricating oils.

In the preparation of lubricating oils, difticulty is frequentlyencountered by the. formation of emulsions during the treatment of thelubricating oil distillates with acid and alkali.` These diliiculti'esinclude ineffectual Vneutralization of the organicacidity in thelubricating oils, a material loss in yield sutfcred through the removalor drawing oli of the emulsilied oil, a material drop in color duringbrightening operations, and a lack of color stability in the finishedoil. These troubles are especially pronounced when the stock used toproduce the lubricating oils is from an asphaltic or mixed-base crude.

Various causes have been ascribed for these emulsions;' chief of theseare: The production of certain reaction compounds during the acidtreatment, and the presence inthe oil of solids .in inely-divided statein suspension, or solids in colloidal form or state as distinguishedfrom solidspresent in true solution. lVliileit is undoubtedly true thatboth of these causes are present, it' has been determined that a partialcause of the more-permanent emulsions encountered in the production oflubricating oils is due to the presence of certain tarry, heavy andasphaltic bodies, particles and constituy ents carried over with thevapors from the distilling equipment in the form of a inistV or spray.The carrying over of these tarry particles or .mist with the vapor ises. pecially lprevalent when the distillation is carried on under areduced pressure.

Whenthese tarry bodies are carried over into the lubricating oildistillates, not only arev additional emulsion troubles encountered, butthe acid treating yield is mate# Arally lowered, required color is morediiticult to obtain, andv greater skill on the part of the treatingoperators is required in order to produce an oil meeting the requiredstandards. Furthermore, the resulting lubricating oils invariablygive apoor precipitation test.

In the distillation operation for the production of lubricating oildistillates, very materialadvantages are obtained' ivhen the entirecomposite or crude lubricating oil stock, comprising the light as wellas the 1923. Serial No. 666,475.

heavy lubricating oil constituents, is fed into a single distilling unitoperated continuously and at a uniformor constant temperature for thevaporization therefrom of all the ditt'erent lubricating oilconstituents. When the distillation is thus conducted, so that thevapors from the higher-boiling-point oils are evolved simultaneouslyand-in a commingled state with the vapors of the xlower-boilingpoint.oils the temperature at which the higher-boiling-point oils can bevaporized is materially reduced. When such distillation is conductedcontinuously and at reatly re duced pressure and preferably with the useof steam, the temperature at vwhich the.

state?, there will be an increased tendency to q carryover with theevolved vapors a mist comprising the undesirable tarry particles beforereferred to.

It will also be apparent that when the advantages 0f the singlecontinuous distillation operation under vacuum are employed and thevapors of the high-boiling-point oils and the l'ilovver-boiling-pointoils are evolved simultaneously and in a commingled state, a subsequentseparation of the evolved products intothe various desired grades oflubri cating o il fractions becomes necessary.

In order to thus employ the distillation advantages incident to evolvingsimultaneously and in a commingledk state, all the vapors ofthe variouslubricating oil distillates and at the saine operation to obtain clean,well-fractionated and yse arate grades of lubricating oil fractions ordistillates, free from the tarry constituents or mist which are' carriedover in the vapors during the distilling operation, I extract from thecommingled evolved vapors this mist before fractionation or condensationof the vapors.

Furthermore, through use of such mist extraction and tractionalcondensation, as employed in my invention. l am able to eliminate fromthe resulting lubricating oil distillates, substantially all of thelight oils, such as gas oil, residual lamp oil and other lightconstituents which have remained in the crude lubricating oil stock fromformer topping operations and which, it permitted to remain in thelubricating oil fractions, would lower the flash-point ot the oils tosuch an extent thativhen the desired viscosity is reached in a givenlubricating oil fraction the Hash-point would be too low to meet therequired specifications and a rcrunning or reducing distillationoperation will be necessary to eliminate such light and undesirable oilsand bring the Hash-point up to requirements.

My invention thus makes possible the operation of a single continuousdist-illinp; unit under a reduced pressure less than atmospheric. andthe simultaneous production ot a number of different grades otlubricatingr oil distillates Without the necessity .tor condensing theevolved vapors in a eonnningled state and subsequently separat-ing thevarious stocks by fractional distillation. and also Without thenecessity of reducing the separate tract-ions tor the requiredtlashpoint. in addition to having the required Hash-point correspondingto the viscosity of the respective distillates. these oils are tree fromthe tarry constituents or mist which promote emulsion troubles duringsubsequent chemical treatment. Due particularly to the extraction of thetarry constituents, particles or mist trom the commingled vapors beforecondensation, an increased treating yield and a better precipitationtest are obdit "tained on the resulting oils than could be otherwiseobtained. l

The invention in its severalaspects may be better understood andcomprehended in connection with a description ot' a process comprising apreferred embodiment of the invention, and by reference to theaccompanying drawings which illustrate apparatus in which may beperformed such a process. The indicated apparatus is given forillustrative purposes only, and it is to be understood that thcarrangement shown and the details oit construction illustrated may beWidely varied Without departing from thescope ot my invention.Furthermore, the invention in its several separate aspects is ot thescope set forth in the appended claims and not necessarily limited ineach of its re spective aspects to all of the steps detailedv in thedescription of a process comprising a preferred embodiment ot theinvention.

lln the drawings: lin Fig. 1 l have indi- V:ated an apparatus by meansof which a process embodying my invention may be peritormed. ln theapparatus as describedv in this gure, lt haveillustrated means tor prenmais?? -fore its introduction into the vaporizing still. Fig. 3illustrates a form ot fractionating` condenser which may be employed. Fi4 illustrates a rc-l'xeating 'tractional condenser which may be employedas a part ot' the apparatus. Fig. 5 is a sectional plan view ot themeans employed for extracting the talrlfv particles or mist from thevapor; and Fig. 6 is a ltmgitiulinal vertical Isection thereof.

Referring to Fig. l:

i-represents a storage tank or source ot supply. 3 represents thefeed-line ot the s vstem in which is a suitable pump 4. 'tor supplyingthe. oil to be distilled through the feed-line 3 under suitable pressureand by ivhich the desired velocity ot flou' is maintained. '.lhefeed-line 3 passes through a vapor heat exchanger 5, ot ordinary or anypreferred construction. and thence passes through a residuum heatexchanger (i. ot' ordinary or any preferred construction. and thencethrough the heating coil 7. Thisl heating coil is mounted in a suitablefurnace 8 and heated by suitable means. such as, for example. aburner-9. From this heat ing coil 7 the heated oil passes to a still orvaporizing` chamber 10. In line between the coil and the outlet into thevaporizing chamber 10, I intel-pose a. suitable pressure controllingvalve l2, which may be set to maintain such pressure as may be desiredor required. '.lhe form, shape or design ofthe still 'orevaporatingchamber l() may be varied as desired, and its form or shape orconstruction forms no part of the` present invention. As shown, thisstiller evaporator 10 is mounted over a suitable furnace l?) providedwith heating means, such as a burner 14. iln p "actiec, the evaporatormay be heat-insulated to prevent radiation losses` l5 represents thevapor outlet line which passes troni the evaporator 10 to the mist"`extractor 85. This mist extractor is preterably in drum torin and theinterior chamber thereof is provided with a suitable number ot seriesoit' vertically arranged channels '86. These channels arc preferablyformed surfaces @it 'the channel-irons causes 'a pre- Cpitationof thetarry constituents,particles or mist which are' Withdrawn from the mistextractor throughvthe oiitlet 87 and conducted by the pipe or conduit 88back into the evaporating chamber or still 10, preferably at or near thebottom` thereof. From the outlet .side of the mist chamber .the vaporline 15 extends through the vapor yheat,eiiclianger 5 and thence to theinletchamber 3() of the reeheating fractional condenser31. Fromthis'inlet chamber 30 the vapors pass through the tubes 32 into theoutlet chamber 33 and thence by the pipe 34 to a second fractionalcondenser 3 5.'

.ber 39 are mounted a series of pans 40 preferably circular incross-section and suitably mounted in the'fcondenser 31, as by suitablebrackets or straps (not shown) welded to the inner shell of thecondenser 31. Between adjoining pans 40 are interposed horizontalpartitions 41 welded to the inner surface of the shell 31. These shellsare proextractor i connections as shown in Fig. 2 may be readilyconnected to. and used in the apparatus indicated in Fig. 1, I have notdeemed it necessary to vextend and show the same in` Fig. 1; 50, 51, 52indicate respectivel the conduits or lines leading from thel owerportions of the condensing chambers of the condcnseis 37,35, 31,respectively. These respective conduit lines 50, 51, 52 are connected(as indicated in Fig. 2) through suitable cooling coils in coolers 46and thence through suitable look-boxes 47 torcceiving drums 48 andthence to distillate storage tafnksor drums C, B, D, respectively. Eachof the receiving drums is connected with the vacuum pump 20. 53represents a condensate line leading from the chamber of the condenser31 and is in turn c0nneet-ed through a suitable coolin coil 45 in acooler 46,A through Va suitable ook-box 47 and to 'a suitable receivingdrum 17 and thenee'through a distillate pump andZ line to a-.distillatestorage tank A. 54 represents vided at. their centers with flangedopenings as shown, of less size ol' diameter than the size or diameterof the pansl 40. The rising vapors from the inlet pipe 38 are thuscaused to pass through a curtain of descending con-v densate dropping'from the lower partition 41 to the lower pan 40 andF through successivecurtains of descending condensate in passing around successive pans andup though the openings in successive partitions 41 and into thevapor-line 42. This vaporline 42 is jconnected vvvith'ra finalfractional condenser 43, from which condenser the lightest distillateproduced is withdrawn. 44 indicates the pipe or liney by Vwhich the saiddistillate is Withdrawn from the condenser 43. `rIhis pipe or conduit 44is connected to a suitable storage tank (not shown) passing firstthrough a suitable'cooling coil 45 (see Fig. 2) in a suitable cooler 46and thence through'look-boxes 47 and a receiving drum 48. This receivingdrum is connected by a suitable'line with a distillate storage tank E,.asuitable suction-pump 4Q being interposed in this line. The receivingydrum 48 is connected by a suitable line 21' witlrthe vacuum pump 20. 22(Fig. 2) represents the exhaust rfronrthe vacuum pump. As this latterand apparatus and nected with a suitable source of supply (not shown). This cooling medium vis preferably water. As indicated in both Fig. 1 andFig. 2, the direct line. of this conduit 54 1s Ithrough the valve 55,coil 56 in the chamber 39 of the re-lieating .fractional condenser 31,

and thence back 'to discharge. A ybranch line 57 leads through a valve58 into the cona cooling medium supplying conduit condenser 43, passingdownward through the tubes or pipes 59 thereof and out through theconduit 60 into the return leg of the line 54.- 61 represents a valve inthis line. The inlet portion'of the line 54 is connected just. beyondthe' branch 57 with a branch line 62 which communicatesL into thedischarge conduit 60 below the condenser 43.

63 represents a suitable valve in this line. Freni the feed-line 3 leadsa branch pipe 64, by means of which the. relatively cool oil to betreated lnay be used as a cooling medium for the condensers f 35, 37.'By using such feed-oil as a lcooling medium in such condensingoperation, heat economy is effectedand the feed-oil after passingthrough the condenser 37 and thence thel condenser 35,

is returned to the line 3, at raised telnperature, by the return leg '65of such conduit. 66 and 67 represents suitable valves controlling thisconduit. The branchconduit 64'is connected directl' with the con` denser37, and the feed-oi after passing downward through the tubes thereof,`passes into the returnv leg 65 through the pipe' 68. A-branehl 69.1eadsfrom `the line 64 to the condenser 35, and `the condenser 35 isconnected-at its bottom by a pipe270 with the return leg 65'. '71represents a branch pipe orl conduit connected with the line 64 betweenthe branch, 69tl1ereof and the con.- denser 37. 'This branch line 71. isconnected with the outlet line 68 of the condenser .37.

lll)

' all essentials similar' to that illustrated in Fig. 1, excep't thatthe apparatus and con-y lill 72, 73, 74, 75, 76 and 77 indicate suitablevalves by which the ilow ofcooling medium through this cooling systelnmay be controlled and regulated as desired. 78 indicates a valveinterposed in the line 3 between the branch 64 and the return le v65thereof 'so that by suitable regulation o the valves 66, 67, 7 8, thecirculation'of44 feed-'oil for this cooling system may be controlled anddirected. 27 represents a steam-line leading into the still oreva-porating chamber 10, the end 28 of such steam-line being preferablyin the form vof al perforated pipe located near the bottom oftheevaporating chamber. 29 indicates a valve controlling such steam-line.The steam-line 27 is connected tb :a suitable source of steam supply(not shown).- 23 represents a residuum draw-oli' line which passesthrough the residnum `heat exchanger 6 and through aocooler 25 to thei'esiduum storage 26. If desired,

the oil to be treated may be discharged into a suitablc'evaporating pan-11 inthe upper portion of' the still or evaporating chamberv 10. 8aindicates a steam-line or source`of supply by which, if desired, steammay be introduced into the condensing chamber 39 of the re-heatingcondenser 31. This steamline 84 is connected with any suitable source ofsteam'supply (not shown).

Referring to Fig. 2: The-apparatus as illustrated in this figure of thedrawings is innections for` high iire pre-heating of the feed-oil areomitted. I have, therefore, in these two figures of the drawings usedthe same reference numerals as indicating-corresponding parts. In Fig. 2the oil-cooling and pre-heating branch line 64 is shown as provided witha branch line 7 9 connecting to the feed-line 3 beyond the residuum heatexchanger 6, and the return leg 65 is shown asv provided with a branchline connected with the feed-line 3 beyond the residuum lheat exchanger6.4 A valve 81 is interposed in thefeed-line 3 between the connectionsof the lines 79'and 8O therewith, and the lines 79 and 80arei'espectively provided with valves 82, 83.y lThe oil to be treated,after passing through the feed-line 3 and. residuum heat exchanger 6,may by means ofre'gulation ofthe valves 81, 82, 83, be passed into thecooling branch line 64 and back into the ,line 3`by the return leg 80,thus utilizing the partially heated oil when so desired.-

In the preferred embodiment of my invention in a process of distillingthe composite lbasic stock containing all ,the diderent'lubi'icating oilfractions to produce lubricating distillates ready for treating andfinishing as lubricating oils, the first step is the pre-heating of suchstock to be treated to a muchl higher degree than can economically beobtained by the use of heatl exchangers .tional heat after the' highrecaer? by which the waste heat of the system is utilized, i. e. :attemperatures below 400o F. I have found that a material increase inthe,rate of evolution ofthe commingled vapors from this composite stock isobtained, giving an increased yield for the same charging creasedcharging rate, when the stock Vfeddnto the distilling chamber ispre-heated to temperatures higher than can leconomically be obtained bythe use of such waste heatfl 'rate orfor the saine yield, permitting aniiivaporizing chamber held at pressuresless than atmospheric.. Thispre-heating mayor may not be carrled on in the presence of steam orwater vapor, the vaporizing chamber may or may not be supplied ilvlithiddi'i y preeate oi is injected therein, and the vaporization may or maynot be carried 'on in the resence of steam. 4I, therefore,'pass thebo yof' oil to be distilled through the'heating element 7 in relativelysmall streams-v and maintain as high a velocity of theoil passingtherethrough as is consistent'with the heat'trans.-

fer from such heating element'to the oil and the"mechan`icalconditionsand adaptations of the particular apparatus and discharge theheated oil into the va'porizing chamber as quickly as possible after ithas been raised to such temperature. I maintain such a pressure of theevolved vapors in the heatingcoil and rlconduit to the vaporizingchamber as maybe required under the conditions of operation tosubstantially maintain the oil as it is bein heated, and when heated,substantially al in liquid phase. Vapori'zation of such heated oil iseffected in .a single vaporizing chamber under a reduced pressure lessthan latmospheric. Under certain conditions of operation I havedistilled oil in accordance with myprocess with as high as`26 inchesofvacuum in the vaporizmg chamber.

In a modification of my preferred process,

the oil, instead of being heated in the heat-` ing element to thehighest degree of tempe-rizing chamber 10 so that the heated oilis not'subjected to such cracking temperature for a sufficient time topermit'of the cracking reaction. ln such case, if the insulation of thevaporizing chamber 10 is sufficient, it may not be necessary to supplyany exterior heat whatever to the vaporizing chamber to vaporize thedesired fractions. Heat may be supplied to such vaporizing chamberlO'byv means of external heat, as, for example, the furnace 13 andburner 14, to impart to the oil loss of heat by radiation orevaporization or to impart additional heat so long as the heat demandupon the shell of the evaporating chamber is not sufficient to causesubstant-ial cracking ofportions ofthe oil undergoing distillation. Withsuch fired pre-heating-of the oil, where using certain California oils,I have found by raising such oil in the heating element to thetemperature of T500-800 F., and retainingthe same in liquid phase,immediately injecting such heated oil into a. vaporizing chamber undervacuum, vaporization of the desired frac- -tions of the oil takes placewithout cracking. If, however, it is desired tovaporize ahigher-boiling-point or more viscous fraction. or fractions, someadditional .heating may be required in the vaporizing chamber. \Vithoutsuch 4additional heat supply in the vaporizing chamber, the resultantliquid oil may be maintained therein at substantially 630 F.Temperatures even above 630 F.

have been thus attained in the liquid body inv such vaporizing chamber.If only the heat lost byi radiation is supplied to the vaporizingchamber, this temperature ofthe oil in the vaporizing chamber is helduniform, i. c.,there is no differential temperature between the body ofsuch oil and the shell of the vaporizing chamber; Furthermore, byapplying additional heat to the vaporizing chamber 1nany degree lessthan sufficient to cause cracking or decomposition at the Contactbetween the shell of the vaporizing chamber and the oil therein, a stillhigher temperature may be maintained in such oil body. By thusdelivering the oil to be distilled into the vaporizing chambeijat suchincreased tempera-ture,

I am able trikv attain a marked increase inthe charging rate/ and,therefore, en increased capacity for the production of highboiling-pomtand high-viscosity'oils. Also I am able to cut deeper and produce morehigh-boiling-point and high-viscosity oil from a given stock. In certainruns the rate of charging must be properly proportioned to permit thevaporization'of such higherboiling-point and higher-viscosity oil. Thelubricating oil thus produced is of a marked superior quality. Asidefrom having a high boiling point and a higher viscosity, dueto highertemperatures' and deeper cuts employed, I produce .a higher-viscosityoil due to the absence of cracking compounds. A better color is alsomaintained andthe treating loss will be found to be reduced.

- If, however, it be not desired to utilize t is feature of high liredpre-heat and maintaining the oil in liquid phase by pressure during suchpre-heat and the=immediate discharge of the highly pre-heated oil intothe vacuum chamber before cracking takes place, I have found that theoil can be subiected to a progressively increasing heat materiallyhigher than that obtained by the use i of waste heat exchangers, but toa lower temperature than that .obtainable inthe heating element 7 asheretofore set forth. For example, utilization of the waste heat of theoperation lcannot economically be utilized ,to raise the oil to bedistilled to above 400. 'F. Additional heat may be supplied to the oilby means of the heating element 7 to raise the temperature thereof toany desired degree below the crackin temperature 4of 'any appreciableportion t ereof, and if such temperature is not sullicient for thevaporization of the desired liigli-boiling-point, high-viscosityfractions desired to be distilled, the required'additional heat can thenjrs besupplied in the vaporizing chamber without danger ofcracking,.inasmuch as the temperature of theoil has been rals'ed to suchan approximation of the temperature of l L the desired distillingoperation that the heat differential between the body of oil to bedistilled as injected into such vaporizing chamberv and the -shelltemperature required for the required heat transfer from the vaporizer10 to the oil is not suiiicient to cause such an abrupt' and excessiveraise in the temperature of the-oil particles in contact with the heatedmetallic surface as will cause cracking thereof. I am, therefore, inthis modified embodiment of this pre-heatinlg step of my invention, ableto conduct suc distillingoperation at ahigher temperature withoutcracking than has heretofore been possible. Increased capacity,increased charging rate,- or deeper cut, is thus rendered possible.

It is obvious that this highly pre-heated oil maybe injected into thevacuum vaporizing chamber either above or into the liquid therein.

onto a spreading-pan, as indicated at 11 in the drawings,o1"other-spreading or distributing means. From the foregoing it is seenthat this step of high red pre-heating of the stock to be distilledcomprehends in lts several aspects the continuous distillation at apres?y without the presence of water vapors or steam and to atemperature higher than can be economically obtained by' the use of heatexchangers utilizing the waste heat of the system, i. e.: totemperatures between 400 F. and 800 F., injecting Vsuch heated oil intoa chamber maintained at a pressure less than atmospheric, which chambermay or may not be supplied with additional heat, depending upon thedegree to which the oil has been heated before interjection therein, andin which chamber additional steam may or; may not be injected,aspreferred,-the manner of injecting the highly heated oil into the vacuumvaporizing chamber being preferably above the surface of the liquidtherein in such a manner as to expose the maximum vaporization surfaceto facilitate distillation, although if desired such injection may bebelow the surface of the liquid therein. Also the step comprehends acontinuous feed, a continuous vaporization and continuous withdrawal ofthe evolved vapors, and the withdrawal of the residual unvaporizedproduct either continuously or intermittently, as desired.

Preferably, all of the vapors to be distilled from the stock arevaporized and pass olf the oil together. 'Ihe mixture of relativelyhigher and relatively lower-boiling-point oils all vaporizedsimultaneously will be found to have the effect of vaporizing relativelyhigher-boiling-point fractions than would be vaporized at the giventemperatures were such higher-boiling-point fractions vapor# izedalo-'ie after the vaporization of such l relatively lower-boiling-pointfractions. All

porizing c amber intermingled and pass to of such va ors are withdrawnfrom the vathe condensing apparatus. It is obvious that after thesevapors have been so produced, the tarry particles, constituents or mistmay be separated therefrom by a' mist extraction as by the mistextractor at any preferred time before passing to condensation. Forexample, while I have shown such mist extractor 85 as arranged i in thevapor-line 15, the mist extractor may be arranged Within the vaporizingchamber or still 10 or as a dome thereof or in any other suitablerelation'to the Withdrawal of the vapors from the chamber 10,

and prior to condensation of such vapors.

rlfhe next step of my invention is to se arate and segregate theintermingled re atively lower-boiling-point and relativelyhigher-boiling-point oils Y contained in the intermiingled y vaporswithdrawn from the recaer? vaporizing chamber. It is highly advantageousto effect this separation in such manner-and under such conditions thatthe producedl condensates will be distillates of the desired boilingpoints and viscosities and not require re-running or reducing to providea stock ready for treating and finishing as lubricating oil; also toremove from the respective distillates those lighter andlowerboiling-point constituents which Aserve A t( contaminate thedistillates produced byv lowering the flash-point thereof.

In the preferred embodiment of a process embodying my invention,therefore, I prefe] to utilize the high heat of the interminglei vaporsas withdrawn from the vaporizing chamber as a means for re-heating thecon densate of the'relatively loweiboiling-poi1n oils. I, therefore,pass these intermingler vapors through closed conduits centaine( withina chamber, to which chamber is re turned the vapors of the lighter orlower boiling-point fractions, said returned vapor; being brought to alower temperature by z controllable cooling means located within sai(chamber whereby a refiux results from sah returned vapors, andre-heating this reflu: through the meansl of the heat of the total interi'ningled evolved vapors passing from th evaporating chamber orestillthrough sah passages of said chamber, thereby revaporiz 'ing andseparating from such reflux thos light fractions which are low infiaslrpoinl This step of the process may he more read ily understood inconnection with the de tailed explanation of such preferred embodi ment.I will, therefore, trace the course o passage of the withdrawninter-mingle vapors of the distilling operation throng the steps ofcondensation and segregatior The highly heated vapors first pass into thchamber 30 of the re-hcating fractional con denser 3l and pass throughthe tubes 3 thereof into the chamber 33. 'lhe descend ing condensatefrom the upper chamber 3 contacts with the tubes 32 highly heated b; thepassage of the vapors therethrough, an this condensate or reflux is thusre-heate and those light fractions which are low i: Haslrpoint arerevaporized and the result ing condensate from Which they are sepa ratedis withdrawn through the pipe or cor duit 52 to the distillate storagetank D. Th effect of this heat transfer is to cause eert-.1incondensation of the highest-boiling point vapors in the'chamber 33.rlihis cor densate is drawn off from the chamber 3 by the pipe 53 to thestorage tank A. 'Ih vapors passing from the chamber 33 throng theconduit 34a and into the condenser 3 are further cooled therein andthe-eender sate forming therein iswithdrawn throng the pipe 5l to thedistillate storage tank I rIhe vapors passing from the condenser 3through the pipe 36 to the condenser 37 ai ily be seen that by thiscontrollable fractional condensation of the ,intermingled `vapors ofdistillation I am able to produce distillates-of the desired boilingpoint range substantially free from low-flash-point oil, and that eachof these distillates isl coinpletely distilled and forms an oil readyfor treatment and finishing as .a lubricating oil. Re-running orreducing is obviated.

While in the preferred process forming a preferred embodiment of myinvention I prefer to utilize the relatively 'cold fresh feed of the oilto be distilled as the cooling medium for the condensers, (such ascondensers 35, 37,) of the intermediate distillates, and to use-.Watercirculation as fthe cooling medium for controlled regulation of thecondensation in the initial or final condensers, it is obvious that anycontrollable cooling medium may be used for these pur-g poses, and theinvention is not necessarily limited to the use of either water or ofthe fresh feed stock as the cooling medium.

I claim: y 1. In the art of petroleum distillation, 'heating the oil tobe distilled to the temper ature at Awhich portions thereof would crackif maintained at such temperature fora period of time sufficient toermit the cracking reaction to take place w ile maintaining the same insubstantially a liquid phase, passing `the heated oil before substantiallcracking thereof takes place to a vaporizi'ng chamber maintained undera reduced pressure less than atmospheric wherein the temperature of theoil is permitted to drop below the temperature at which port-ionsthereof would crack, withdrawing'vapors from said" chamber, extract-ingfrom the vapors the tarry mist without substantial scrubbing of vaporsin said step, and thereafter fractionally condensing the vapors into anum .ber of distillates of different boiling points.

2. In the art of petroleum distillation, heating the oil to` bedistilled to a vtemperature at which portions thereof would crack ifmaintained at such temperature for period of time sufficient to permitthe cracking reaction to take place, while maintaining the same insubstantially liquid phase, immediately pgassing the heated oil beforesubstantial cracking thereof takes place to a vaporizing chamber,maintained under' a re'- duced pressure lessthan atmospheric, Whereinthe temperature of the oil isi-dropped below the temperature at whichportions would crack, extracting .from thevapors the tarry mist withoutsubstantial scrubbing of vapors in said step, and .thereafterfractionally condensing the vapors. into a .number of distillatesofdiiferent boiling points.

3. In -the art of petroleum distillation, rapidly passing the oil in arelatively small stream through a heating element, thereby raising thetemperature thereof tothe tem,- perature at which portions ofsaid oilwould 4crack if maintained at suchteniperature for a period .of time,suicient .to permit the cracking reaction to 4 take p1ace,.whilemaintaining such oil in substantially liquid phase by suitable pressure,immediately discharging the heated oil vbefore substantial crackingthereof occurs, into a vaporizing chamber maintainedl under a reducedpressure less than atmospheric, wherein portions of t-he oil vaporize,thereby'causing the temperature of the .oil to drop below the,temperature at which portions thereof 'would' crack,

withdrawing they resultant vapors, suitably Withdrawing` the resultantunvaporlzed product, yextracting from the vapors the -t'arry mistWithout substantial scrubbing of-vapors in said step, and thereafterfractionally condensing the vapors 1nto a number of distillates ofdifferent boiling points.

Signed at Richmond, California, this 25th day of Sept., 1923.

RICHARD W; misiva`

